1. Field of the Invention
The present invention relates to a CAD/CAM unit data generating process which allows data for efficient machining to be generated independently of a shape defining sequence.
2. Description of the Background
FIG. 9 is a block diagram illustrating the configuration of a CAD/CAM unit known in the art. The unit has an input device 1, comprising one or more of a keyboard 2, a mouse 3 and a tablet 4, that is employed for entering shape information (e.g., round, square, height etc.), character information, etc. A shape defining section 5 is used for converting the entered shape information into data corresponding to an internal storage format. A machining defining section 6 is where machining information, used for starting and finishing a shape in correspondence with the entered shape information, is generated in response to character information from input device 1. A shape information memory 7 is used for storing the output of the shape defining section. A machining information memory 8 is used for storing the output of the machining defining section 6. A process analyzer 11 sequentially analyzes the shape information and machining information output by the shape information memory 7 and machining information memory 8, respectively. The analyzer 11 then determines how the workpiece is to be machined. A NC information generator 12 decides upon an appropriate machining path in accordance with the information analyzed by the process analyzer 11 and generates NC control data. A NC data file 13 is used for storing the NC data generated by the NC information generator 12. A machining path display 14, that performs display processing of the NC data, is also operative to control the display on a CRT 15 of the machining path.
Operation of the conventional CAD/CAM unit will now be described. First, an operator controls the keyboard 2, mouse 3 and tablet 4 of the input device 1 to enter shape information (geometric information such as coordinate values, depths, heights, etc). The input shape information is converted into data corresponding to an internal storage format by the shape defining section 5, then stored in the shape information memory 7. At this time, the shape information is arranged on the basis of one or more machining units. Where plural units are required for a single shape, they are stored in a shape defining sequence.
Information concerning the machining conditions (information such as tool names and feed rates) for each machining unit for a shape, as described previously, also is entered from the input device 1 by the operator. The entered machining information is converted into data corresponding to the internal storage format by the machining defining section 6, then stored in the machining information memory 8 on a machining unit basis and in a shape defining sequence.
The information is stored in the shape information memory 7 and machining information memory 8 in the manner shown in FIG. 10. That Figure illustrates the organization and sequence for storing shape information and machining information so that NC information corresponding to the three-step pocket machining, illustrated in FIG. 11, can be effectively generated. Specifically, the shape information has been entered by the operator in order of shape a, shape b and shape c, and the machining information also has been input in the order a, b, c. The machining information is arranged to have a direct correspondence to its respective shape. As seen in the Figure, it is linked to the shape information and is arranged in a list structure in the same order. In this manner, geometric information such as the coordinate values, depths, etc. of each shape is stored in the shape information memory 7, and tool names, feedrates, etc. employed for the machining of each shape are correspondingly stored in the machining information memory 8.
The information in the shape information memory 7 and machining information memory 8 is then analyzed by the process analyzer 11, sequentially. At this time, retrieval is made in accordance with the list structure and therefore the information is analyzed in order of shape a, shape b and shape c. The analysis identifies relative heights, sizes and geometries of the several shapes and may prioritize or weight the several shapes.
A machining path is then determined by the NC information generator 12 in accordance with the analysis results of the process analyzer 11. The selected machining path is written to the NC data file 13 in the sequence from shape a to shape c. The data defining the selected machining path may be processed by the machining path display 14 for display of the selected machining path on the CRT 15.
In the conventional CAD/CAM unit data generating process carried out as described above, the machining sequence is set according to the shape defining sequence. However, in practice, shapes alone cannot determine the machining sequence, particularly where the shapes are complex. To carry out efficient machining, shapes often are defined after the machining sequence has been examined in detail. Because of this interrelationship between the shape and machining sequence, a significant amount of time is required for the generation of NC data, thus resulting in an inefficient operation. Moreover, when the shapes are complex, or closely similar in size or contour, errors can occur such that the proper order of machining is not followed, e.g., the highest point in a workpiece is not machined last.
It is, accordingly, an object of the present invention to overcome the disadvantages in the conventional unit by providing a CAD/CAM unit data generating process which allows data to be generated efficiently, independently of the sequence of shape definition.